Fabric containment constructions

ABSTRACT

A dual-wall fabric is provided, with integrally woven drop stitches connecting opposite walls thereof, the fabric being adapted to receive a filler material between walls thereof, the filler material being preferably cast therein, such as concrete, and the fabric walls being of desired materials and weaves to yield desired porosities. One or both of the walls may be constructed of a material having a specific gravity less than water, to facilitate floating of the same in water. Prior to filling the dual-wall fabric with concrete or the like, reinforcing rods may be interspersed between the connecting drop stitches. The dual-wall fabric, or a single-wall fabric may be anchored along beaches, canals and the like, into canopy-like configurations or structures, which structures may be filled with sand or other natural fill, the mound or sand bar thus formed being then covered by a concrete-like material. In the case of a dual-wall fabric construction, concrete may be pumped between the fabric walls, to provide a concrete-like outer encasement for the sand bar or the like thus formed.

[451 June 20, 1972 FABRIC CONTAINMENT CONSTRUCTIONS [72] Inventors: JohnT. Hayes, Durham; Robert G. Curri- Y er, Roxboro, both of NC.

Collins and Aikman Corporation, New York, N.Y.

[22] Filed: Feb. 5, 1968 [21] Appl.No.: 702,925

[73] Assignee:

[52] US. Cl ..61/3, 61/5,61/37 [51] Int. C1... 021) 3/04 [58] FieldofSearch ..61/37,37,38, 61/47; 139/20, 410; 52/2; 160/178 E [56] IReferences Cited UNITED STATES PATENTS 2,209,874 7/1940 Dempsey 139/4102,632,480 3/1953 Maclntyre .....139/410 877,201 1/1908 Kellner ..61/31,815,196 7/1931 French 6! a1. ..160/178E 2,185,458 1/1940 Giliasso..61/5 2,657,716 11/1953 FOld 139/410 2,939,467 6/1960 Meyer et a1.....52/2 3,008,213 11/1961 Foster 61 .139/410X 3,188,813 6/1965 Foster etal. ..61/5

3,224,466 12/ 1965 Grover ..139/20 3,299,640 1/1967 Neilsen ..61/33,396,545 8/1968 Lamberton ...6 1 /47 3,425,228 2/1969 Lamberton...6l/38 Primary Examiner-Peter M. Caun Attomey-Paul & Paul [57]ABSTRACT A dual-wall fabric is provided, with integrally woven dropstitches connecting opposite walls thereof, the fabric being adapted toreceive a filler material between walls thereof, the filler materialbeing preferably cast therein, such as concrete, and the fabric wallsbeing of desired materials and weaves to yield desired porosities. Oneor both of the walls may be constructed of a material having a specificgravity less than water, to facilitate floating of the same in water.Prior to filling the dual-wall fabric with concrete or the like,reinforcing rods may be interspersed between the connecting dropstitches. The dual-wall fabric, or a single-wall fabric may be anchoredalong beaches, canals and the like, into canopy-like configurations orstructures, which structures may be filled with sand or other naturalfill, the mound or sand bar thus formed being then covered by aconcrete-like material. In the case of a dualwall fabric construction,concrete may be pumped between the fabric walls, to provideaconcrete-like outer encasement for the sand bar or the like thusformed.

4 Claims, 11 Drawing Figures PATENTEDJUHO 1972 3,670 504 SHEET 10$ 3INVENTORS. MULK BY gag S ZEE R !9' 4 fiwzkm ATTORNEYS.

P'A'TE'N'TEflJuuzo m2 3, 70,504

sum 2 or 3 Fig. 6

Fig l 7 INVENTORS.

JOHN T. HAYES BY I ROBERT G. CURRIER paw/PM TORNEYS.

PKTE'N'TEmum 1972 SHEET 30F 3 INVENTORS. JOHN T. HAYES VAN . ILII Cr. 3

- I I W 1. a

BY ROBERT G. CURRIER @flM ATTORNEYS FABRIC CONTAINMENT CONSTRUCTIONSBACKGROUND OF THE INVENTION Dual-wall fabric constructions inthemselves, are known in the prior art, even those having integrallywoven connecting threads, such as are used for inflatable mattresses andthe like. However, the prior art is devoid of any teaching of utilizinga dual-walled fabric construction having integral drop-stitch threadconnections, and which is filled with a filler material, preferably ofthe structural type, such as cast concrete, grout, cement or the like,or even plastics or foams. Furthermore, the prior art is devoid of anyteaching of a dual-walled fabric having integral connecting threads,wherein the fabric, in its finished form is porous, to permit thepassage therethrough of moisture from a castable, filler material, suchas concrete or the like. Still further, the utilization of suchdual-walled or even single-walled fabrics having specific gravity lessthan water to utilize the effect of the buoyancy of such fabrics inwater in order to maintain a canopy-like shape of a fabric sheet duringthe filling of the same with a natural fill, such as sand, for purposesof constructing sand bars, sea walls, groins, cofier dams and the like,is nowhere taught in the prior art.

With particular regard to the construction of sand bars and the like, inmany costal areas and the like, soil erosion and beach conservation arecontinuing problems, with sea currents, tides, etc., continuouslysweeping off the natural fill from the beach surfaces. In many instancessuch erosion is prevented by sinking pilings and the like, or bydropping pilings or tetrapeds into the beach area. However, heretofore,sand mounds formed by prior art techniques have not successfully builtup sand mounds such that the sloping mound surfaces have a greater than25 angle with the sea floor.

Other beach conservation processes have been proposed, but none havebeen adapted toward quick installation resulting from the use ofprefabrication techniques, resulting in economically installed sand barsand the like of a permanent nature.

SUMMARY OF THE INVENTION The present invention seeks to obviate andovercome the above and other deficiencies in prior art dual-wall fabricconstructions for structural purposes and erosion control techniques, inproviding a dual-wall fabric having connecting threads integrally woventherewith, which is adapted to receive a concrete or similar fillmaterial therein, and which permits water drainage therethrough of theconcrete during setting, with various types of drop-stitch weaveconstructions for desirably balancing stresses, and with reinforcingrods being optionally provided.

The fabric may be constructed to have one or more walls of a material,such as polypropylene, which has a specific gravity less than that ofwater, such that the buoyant effect of water would normally tend tofloat the fabric in water. Accordingly, by desirably anchoring such afabric, either of single or of dual-wall construction, such that it issufficiently loose to tend to float, and assume an arcuate shape orconfiguration, the fabric may then be filled either by pumping thefabric with sand or other natural fill, or by utilizing a fabric mesh ofsufficiently loose construction to permit the passage of sandtherethrough, whereby the fabric dome or the like may be filled by thenatural motion of sand or other natural fill along the sea floor. Theanchoring means can comprise concretefilled fabric tubes which areconnected longitudinally to the dome shaped fabric construction, alongedges thereof adjacent the sea floor. If the fabric surface is ofdouble-walled construction, the same may be pumped full of concrete orthe like, after the dome shaped construction is filled with sand, andafter hardening of the concrete, the structure is substantiallypermanent. If the fabric material of the dome construction is ofsingle-wall thickness, a concrete or the like overcovering may beprovided for the dome or sand bar thus formed.

These same principles, such as that of utilizing materials which have aspecific gravity less than water to substantially float the same inwater, for the purpose of sea-wall construction, are also within thescope of this invention, whereby a vertical wall may be formed by asheet of loosely woven'mesh, which is anchored at one end against thesea floor, whereby sand can gradually accumulate against sides of thesea wall, to form a sand bar or the like, the bar being adapted to bethen made permanent by receiving an over-covering of concrete or thelike, if desired.

Accordingly, it is a primary object of this invention to provide a noveldual-wall fabric having a pair of opposed woven fabric layersinterconnected by integrally woven drop stitches, the dual-walled fabricbeing adapted to receive concrete or the like materials therein, forfacilitating the provision of desirable structures.

It is another object of this invention to accomplish the above object,wherein the drop stitches are disposed at a desirable angular relationwith respect to the opposed fabric layers, for distributing stresses andpressures in a desirable fashion, such stresses and pressures resultingfrom the filling of the dual-wall fabric by a desired filler material.

It is a further object of this invention to accomplish each of the aboveobjects, wherein the fabric layers are of selected porosities andspecific gravities, for the respective purposes of facilitatingbreathing of a cast filler material through the fabric walls, and forfacilitan'ng a buoyancy of the fabric when immersed in a liquid, such'aswater.

It is another object of this invention to provide a structural member ofdual-walled fabric construction having integrally woven connectingstitches at desirable angular relationships with respect to the oppositewalls, wherein reinforcing rods are provided interspersed throughout afiller material disposed between the fabric walls.

It is a further object of this invention to provided beach erosion andcontrol structures which may be substantially prefabricated and whichare relatively easy to install underwater, and which utilize, to asubstantial degree, the natural fill of the sea floor in theirconstruction, but which when installed, may be readily made permanent.

It is a further object of this invention to provide substantiallypermanent beach conservation structures and the like, which utilizefloatable fabric materials weighted along opposite sides to form a domeconstruction which, when filled with sand, may be either covered or havean outer surface portion thereof pumped full of concrete or the like, toprovide an artificial sand bar construction.

It is yet another object of this invention to provide a sea-wallconstruction for collecting natural fill thereabout, which may, then becovered with a concrete or cement layer, if desired, but which utilizesa buoyancy effect on the material of construction of an anchored seawall, to maintain the same in a vertical plane underwater, duringcollection of the natural fill thereabout.

It is a further object of this invention to provide a novel method forthe formation of beach erosion-control structures, utilizingconstructions which may be substantially prefabricated and readilyinstalled and completed in situ.

Other objects and advantages of the present invention will becomereadily apparent to one skilled in the art upon a detailed study of thefollowing brief figure descriptions, the detailed descriptions of thepreferred embodiment, and the drawings and appended claims.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a fragmentary top perspectiveview of a dualwalled fabric of this invention, wherein integralconnecting drop-stitch strands are illustrated disposed at acute anglesto the opposed fabric walls.

FIG. 2 is an enlarged fragmentary schematic view of the dual-walledfabric of FIG. 1, as it would appear in view taken along the line H IIof FIG. 1, looking transverse of the machine direction of weave, withthe connecting strands being of repetitive generally X-shapedconfiguration, with a portion of the view being generally indicative ofthe appearance of the dual-walled fabric construction when the same isfilled with concrete or the like.

, FIG. 3 is a schematic end view of the dual-walled fabric of FIG. 1,taken generally in the machine direction along the line III III of FIG.1, wherein the vertical disposition of the angularly disposed connectingstrands, as viewed endwise, is clearly illustrated.

FIG. 4 is a view similar to that of FIG. 3, but of a dual-walled fabricconstruction, wherein a plurality of connecting strands are aligned,transversely of the machine in side-by-side relation, to yield atape-like connecting stitch or web construction.

FIG. 5 is a view similar to that of FIG. 2, of a drop-stitchconstruction having connecting strands angularly disposed in repetitiveX-shaped configuration, to provide connecting stitches, of web form,sufficient for withstanding to a large degree, pressures which wouldtend to separate opposed fabric layers resulting from applying a fillbetween the opposed fabric layers, but wherein there are illustratedreinforcing rods, disposed throughout the connecting strands, betweenthe fabric walls.

In FIG. 6 there is illustrated a side view of a dual-walled fabricconstruction in schematic form, generally similar to that of FIG. 2, butwherein the individual connecting strands are disposed at right anglesto each of the opposed fabric walls.

In FIG. 7 there is illustrated in side view a preliminary stage offormation of the fabric constructions of FIGS. 2 and 5, prior toseparation of the opposed fabric layers.

FIG. 8 is a fragmentary top perspective view of an artificially formedsand bar formed of a dual-walled fabric of this invention which isprovided with concrete-filled fabric tubes as anchoring means for thefabric during filling of the space between the fabric and ocean floorwith sand or the like, the dual-walled fabric being later filled withconcrete or the like, between its opposed walls to result in a permanentstructure, with an end portion of similar construction also being illustrated.

FIG. 9 is an enlarged fragmentary sectional view taken generally alongthe line IX IX of FIG. 8, wherein the dualwalled fabric of constructionof the bar of FIG. 8 is more clearly illustrated. 1

FIG. 10 is a cross-sectional view, in schematic form, of an underwaterartificial sand bar formation, utilizing a floatable fabric ofsingle-walled construction, the bar structure being otherwise similar tothat of FIG. 8.

FIG. 1 1 is a cross-sectional view of an underwater sea-wallconstruction, in schematic form, wherein the sea-wall is maintained invertical position due to the buoyant effect of the water thereon, whilesand accumulates about the lower anchored end of the sea wall.

Referring now to the drawings in detail, reference is first made to FIG.1, wherein there is illustrated a dual-wall fabric construction,generally designated by the numeral 15, which comprises spaced upper andlower walls or layers 16 and 17, respectively.

The upper wall 16 of the construction 15, as illustrated is preferablyof a loose weave construction the fibrous material being of any suitablematerial, such as nylon, polyethylene, foamed polypropylene, or foamednylon, but preferably of polypropylene fibers, particularly if thefabric is to be used underwater, in applications where it may bedesirable to vertically separate the upper layer 16 from the lower layer17. In the latter instance, the water would have a buoyant effect on thepolypropylene layer 16, due to the specific gravity (0.9) ofpolypropylene, as compared to that of water 1.0).

l The lower wall or layer 17 may be of a more tightly woven I fibrousconstruction, as illustrated, if porosity of this lower layer is notdesirable, as for example, if the lower layer is to be used for sandcontainment, as illustrated in FIGS. 8 and 9. The fibrous materials fromwhich the lower layer 17 is constructed may be nylon, or similarmaterials if desired.

A plurality of connecting strands 18 comprise stitches of thedrop-stitch type, the strands 18 being integrally woven into thedual-wall fabric 15, and comprising the same material as that of theupper wall or layer 16. Thus, if the material comprising the strandswhich form the upper layer 16 is of polypropylene, the connectingstrands 18 are also of polypropylene. It will be noted that there is ahigh density of connecting strands 18 between the walls or layers 16 andl7,for purposes of distributing tensions and pressures, in a manner tobe described below.

With particular reference to FIG. 2, it is seen that the strands 18,formed by the drop-stitch method, are disposed at acute angles ofsubstantially 45 between the upper and lower layers 16 and 17respectively. With reference to FIG. 3 also, it is seen that the strandsl8 lie substantially in common planes, spaced transversely of themachine, or transversely of the direction of fabric travel duringmanufacture. Thus, each strand comprises a dropped warp strand, and isconnected to or woven around transverse strands in each of the upper andlower layers 16 and 17, respectively. With continued reference to FIG.3, it is seen that the transverse spacing of the drop strands 18, 18,18", etc. across the machine, during formation of the dual-wall fabric15 may be altered, as desired, to increase the transverse density of thedrop strands, as desired.

As illustrated at the right side of FIG. 2, the dual-wall fabric 15 isfilled with concrete 21. It is to be understood that the term concrete"is to be construed as being sufficiently broad to encompass cement,grout, mortar, and other similar materials. The concrete 21 may bepumped or otherwise placed between the layers 16 and 17 of thedual-walled fabric 15, in wet form, and allowed to set or become cast"therebetween, such pumping possibly exerting high pressures tending toseparate or more greatly space the upper and lower walls or layers 16and 17, respectively. The greater such pressure from pumping concrete 21into the fabric 15, the more dense should be the placement of connectingstrands 18. As has been set forth above, it may be desirable to have theupper layer 16 to be less dense than a lower layer 17, with respect tothe weave construction, in order that the upper layer 16 may be moreporous, to permit the passage of moisture or water therethrough as theconcrete 21 becomes set or cast. In some applications, it may bedesirable to have both upper and lower layers 16 and 17 to besufficiently porous for this purpose, but in some instances, if thefabric 15 is to be used as an uppermost covering for an artificial sandbar, such as that of the type illustrated inFIG. 8, it is most desirableto have a lower fabric surface 17 of tight weave construction, to retainsand particles therein, but to have an upper fabric layer 16 of looseweave construction, to contain the concrete therein, but to permit thepassage of excess water therethrough.

It is to be noted that the fill need not be concrete 21, but in manyinstances and applications the filling material may desirably be asuitable hardenable plastic, or foam, such as polyurethane foam.However, regardless of the filling material, foam, plastic, concrete orthe like, such will have sufficient qualities for immersion of theconnecting strands 18 therein.

With particular reference to FIG. 4, it is to be noted that a pluralityof strands 22, 23, 24, 25 and 26 may be aligned in side-by-siderelation, threaded into a repetitive X-shaped side view configuration asillustrated in FIG. 2, if desired, the end view configuration of FIG. 4being particularly illustrative of an embodiment whereby severalconnecting strands 22, 23, 24, 25, 26 are operative, each similar to anindividual connecting strand 18, but wherein the several strandscooperate to form a tape-like connecting stitch or web between spacedupper and lower fabric walls 27 and 28, respectively.

In FIG. 5, there is illustrated a dual-wall fabric, generally designatedby the numeral 30, similar to that 15 of FIG. 2, and having spaced upperand lower walls or layers 31 and 32, respectively, interconnected bydrop threads or strands 33, also disposed at acute angles with respectto the upper and lower walls 31 and 32. In the embodiment of FIG. 5, aplurali ty of reinforcing rods 34, 35, 36 and 37, are illustrateddisposed in spaced relation to each of the walls 31 and 32, and

retained in such positions by the crossing connecting strands 33. Thus,a structure such as that 30, may be used for other constructionpurposes, being reinforced with steel or iron rods, cables or the like,if desired, prior to filling the fabric 30 with concrete (not shown) orother filler material. Such rods may be hollow for carrying power andcommunciation wires and cables, water pipes, steam lines, etc.

In FIG. 6 there is illustrated another alternative embodiment of adual-wall fabric 40 comprising upper and lower layers 41 and 42,connected by individual or plural strands 43, disposed between thelayers 41 and 42, at substantially right angles to the plane of each ofthe layers 41 and 42, such strands 43 being formed by a straight throughdrop stitch method, should the same be desirable. The dual-wall fabric40 may also be filled with concrete or the like, as desired.

In FIG. 7 there is illustrated a basic weave formation 50 used to attainthe dual wall fabrics or 30 of FIGS. 2 or 5, respectively, havingopposed layers 51 and 52 connected by drop strands 53, illustrated atsmall acute angles with respect to the layers 51 and 52, prior toseparation of the layers 51 and 52 an amount such as those layers 31 and32 of FIG. 5, for example, and thus prior to the strands 53 taking onthe X-shaped configuration of the strands 33 of FIG. 5. The strands 53may be woven with various heights of gage wires 54, depending upon thenumber of crossings of the gage wires 54 and the height of the gage. Thedistance between the fabric layers 50 and 51 can be any desired height,to attain the desired layer spacing of FIG. 5, for example. A normaldistance between the layers 31 and 32 would be within the range 0.5 to24 inches.

With particular reference to FIG. 8, there is illustrated, in finalformation, an artificially fonned sand bar or the like, generallydesignated by the numeral 60, disposed substantially entirely beneaththe upper surface 61 of water 62, as on a beach or the like, having afloor or lower surface 63, of sand or like natural fill material.

The bar 60 is adapted for channels, beaches, or the like, and may havean uppermost portion protruding out of the water 62, above the surface61 thereof, as illustrated, if desired. The bar 60 is formed by a canopy64 being provided, of a plurality of longitudinal portions 65 of adual-wall fabric 15, (as illustrated in FIG. 1) stitched together alongseams 66, and along opposite longitudinal edges 67 and 68 thereof havingtubular fabric portions connected thereto as by stitching, or the like.Such tubular fabric portions are designated by the numerals 70 and 71,respectively. At the end of the canopy 64 formed by the plurality offabrics or sheets 15, is an end cover 72, which also comprises aplurality of fabric portions 73, stitched together along seams 74 andalong the arcuate edge 75 at the ends of each of the portions 65, toclose the end thereof. At the lowermost end of the end-wall fabric 72,there is provided a tubular fabric construction 76, stitched theretoalong a edge 77 thereof, similar to those tubular members 70 and 71stitched along the sides of the canopy 64. Thus, the entire fabricconstruction illustrated may be prefabricated, and carried to the areaof installation, as on a boat or the like, from which is may be droppedinto the water 62, onto the sand surface 63, the tubular portions 70, 71and 76, being pumped full of concrete or the like, to provide weightedportions, for retaining the canopy 64 in position. Due to thelighter-thanwater material of construction of the canopy 65, or at leastof the upper surface 16 thereof, the buoyant effect of water thereonwill tend to fill out the shape of the canopy 64 into a generallyarcuate configuration, as illustrated in FIG. 8, up to the height of thewater surface 61, at which level the canopy fabric would remain untilthe interior of the canopy 64 is pumped full of sand, or is otherwisefilled with sand or other similar natural fill material 78. After thefill material 78 rounds out" the canopy 64, the dual-wall fabric 15, asillustrated in FIG. 9, may then be pumped full of concrete or the like,between the two layers 16 and 17, whereby the connecting strands 18 willbe immersed therein, the water 61 which is present between the layers 16and 17 being forced outwardly through the loosely woven or porous layer16, as the dual-wall fabric fills with concrete 21. Upon setting of theconcrete 21, and setting of the concrete which fills the tubular fabricportions 70, 71 and 76, the sand bar 60 becomes a substantiallypermanent construction. It will be apparent, that the length of the sandbar 60 may be set as desired, the individual fabric strips 65 beingcapable of manufacture to the desired length of a particular sand bar 60to be constructed.

In FIG. 10 there is illustrated a fabric construction 80, generallysimilar to the canopy 64 of FIG. 8, having tubular portions 82 and 83stitched or otherwise secured to opposite longitudinal edges thereof,but wherein the fabric material between the tubular portions 82 and 83comprises a single thickness sheet of polypropylene or otherlighter-than-water materials, or even a dual-wall fabric if the same isdesired. In the embodiment of FIG. 10, the fabric construction 80 ifplaced into the water 84, with the tubular portions 82 and 83 on thebottom surface or beach floor 85 thereof, and the tubular portions 82and 83 are again weighted, as by pumping them full of concrete or likefiller. The buoyant effect of the water 84 on the polypropylene or otherlight sheet 81 then permits the sheet 81 to take on the form illustratedin FIG. 10, to be of arcuate construction. The particular weave of thesheet 81 permits water currents, tidal waters, or the like to carry sandor other natural bottom fill 86 through the loose weave of the sheet 81,such that it will gradually fill the void 87 beneath the arcuate sheetor canopy 81 until the sand takes on an inverted U-shaped configuration.If a temporary bar is desired, the structure may remain as illustratedin FIG. 10, or in the event that a permanent sand bar is desired, thesurface 81 may be then covered with concrete-filled dual-wall fabricssuch as the type illustrated in FIG. 2.

In FIG. 11 there is illustrated an alternative construction, for fomiinga sea-wall, wherein a sheet 90 of loosely woven polypropylene or otherlighter-than-water material is provided, having secured thereto at alower end, a tubular fabric construction 91, which when filled withconcrete or other suitable material and placed on the beach floor 92,beneath the water 93, tends to anchor the sheet 90 in a verticalposition, the water having a buoyant effect on the material ofconstruction of the sheet 90. Additionally, another tubular fabricmember 94 may be provided, secured to the uppermost end of the sheet 90,which may be filled with polystyrene or other buoyant pellets 95, or thelike, to also facilitate maintaining the sheet 90 in verticaldisposition, again utilizing the buoyant effect of the water on thepellets 95 to retain the tubular member 94 directed toward the uppersurface 96 of the water. The structure illustrated in FIG. 11 is alsooperative during natural currents, tides, and the like, whereby sand orother natural fill 97 is conveyed along the beach surface 92, toaccumulate the same on opposite sides of the surface 90, around theweighted portion 91, such sand 97 gradually accumulating upwardly, asillustrated, to form a sea wall, which may then be made permanent, as bycovering the same with concrete-filled dual-wall fabric constructions,such as the type illustrated in FIG. 2, if desired.

It is to be noted that the various tubular fabric portions 70, 71, 76,82, 83, and 91 may be of nylon construction or the like, where thespecific gravity of the same is not critical.

Also, should it be desired to have vent points in a dual-wall fabricconstruction, such may be made by inserting a hollow rubber, orpolystyrene, or like ball, between the walls of a fabric, such that,after the dual-wall fabric is grouted, or otherwise filled withconcrete, the ball may be punctured, thereby providing a hole forsecuring any desired attachment devices to the concrete, such method ofmaking vent points being substantially less expensive than drillingthrough concrete.

It is to be particularly pointed out that an advantageous feature ofthis invention resides in the fact that the restrictive length of thedrop threads or connecting strands prevents ballooning of the oppositefabric walls during the filling of the same with concrete, any of thestyrenes, foamable materials such as polyurethane, or the like, thestrands also being operative for purposes of balancing the stresseswhich would tend toward expansion of the distance between the oppositefabric layers. Thus, the more dense the drop threads are, the greaterwill be the ability of the dual-wall fabric to balance stresses duringfilling thereof.

in those instances where the alkaline content of the concrete, grout,etc. is sufficiently high to have a tendency to react with polypropyleneor the like, thus causing a degradation of the layer fibers, andparticularly of the connecting strands, those strands or layer fibers orboth may be nylon, to eliminate any attendent degradation problem.

It will be apparent to those skilled in the art that variousmodifications may be made on the various fabric containmentconstructions, and in the several specific applications of the samewhich are illustrated, along with changes in their assembly andenvironmental applications, all within the spirit and scope as definedin the appended claims.

What is claimed is:

1. A dual-wall fabric for use in combatting soil erosion, such as in theconstruction of underwater dams, comprising a pair of opposed wovenfabric layers having drop stitches woven integrally with and connectingsaid layers, said opposed layers being constructed of materials whichhave dissimilar specific gravity characteristics which are respectivelygreater and less than that of the water with which the fabric is to beused, such that the fabric, when immersed in water and expanded betweenthe layers, one said layer is disposed buoyantly uppennost in the waterand the other said layer is spaced by gravity from the one said layer.

2. The dual-wall fabric of claim 1 wherein the first said fabric layeris constructed of polypropylene material.

3. The dual-wall fabric of claim 1 wherein the other said fabric layeris of nylon construction.

4. A method of making an artificial waterbreak for beach conservationand the like, comprising the steps of 1. providing a dual-wall fabricsheet material having con necting strands and weighted longitudinaledges in immersed relation, with the weighted edges spaced from oneanother on a below-water surface, a distance less than the width of thesheet material,

2. providing natural fill in the space between the belowwater surfaceand the sheet material to force water from beneath the sheet materialand to fully fill the space beneath the sheet material,

and 3. filling the space between the opposite walls of the fabric sheetmaterial with a hardenable concrete-like material.

1. A dual-wall fabric for use in combatting soil erosion, such as in theconstruction of underwater dams, comprising a pair of opposed wovenfabric layers having drop stitches woven integrally with and connectingsaid layers, said opposed layers being constructed of materials whichhave dissimilar specific gravity characteristics which are respectivelygreater and less than that of the water with which the fabric is to beused, such that the fabric, when immersed in water and expanded betweenthe layers, one said layer is disposed buoyantly uppermost in the waterand the other said layer is spaced by gravity from the one said layer.2. The dual-wall fabric of claim 1 wherein the first said fabric layeris constructed of polypropylene material.
 2. providing natural fill inthe space between the below-water surface and the sheet material toforce water from beneath the sheet material and to fully fill the spacebeneath the sheet material, and
 3. filling the space between theopposite walls of the fabric sheet material with a hardenableconcrete-like material.
 3. The dual-wall fabric of claim 1 wherein theother said fabric layer is of nylon construction.
 4. A method of makingan artificial waterbreak for beach conservation and the like, comprisingthe steps of